Development of framework in the selection and reuse of concrete waste and brick waste powder as pozzolanic material in cement concrete application using analytical hierarchy process technique

Abstract

The utilization of construction and demolition waste (C&DW) for sustainability is a promising area. Globally, there is a growing potential interest in the reuse of waste powder from recycled concrete and bricks in concrete applications. In the current study, the pozzolana criteria were evaluated for three materials: Fly ash (FA), Concrete waste powder (CWP), and Brick waste powder (BWP). Chemical, Physical, and Pozzolanic tests, i.e., Frattini test, Lime Saturation test (LST), Strength Activity Index (SAI) and Electrical conductivity test (ECT), were carried out on the raw material. A framework was developed to select and reuse CWP and BWP in cement concrete applications. An Analytical Hierarchy Process (AHP) was carried out to study the priorities of pozzolana materials based on the road map criteria. One-way sensitivity analysis was performed to check the sensitivity of the properties. Microstructural characteristics such as scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermal gravimetric analysis (TGA) were performed to investigate the morphology, amorphous content, and consumption of portlandite in the pozzolana. In addition, chemical activators; Lime, Sodium Silicate, and Sodium Hydroxide were investigated for their ability to enhance the pozzolanic activity of CWP, and statistical analysis was performed to validate the chemical enhancement. CWP and BWP cleared the road map criteria of pozzolanic activity. Adding (5–7.5%) lime improves the later strength, whereas (2.5–7.5%) NaOH & Sodium Silicate improve the early and later mechanical properties of the CWP-based mix.